Float walls in basement?

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  #1  
Old 12-02-08, 08:53 PM
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Float walls in basement?

Relative newbie building some interior walls in a new basement, and I would like to "float" them from the floor. The house resides on top of expansive clay soil.

Looked around for a good step-by-step approach but couldn't find one. Have floated walls from the ceiling before, using spikes through the top plate and into the joists, and nailing bottom plate to concrete floor. For this though, I think you have to nail an additional plate to the floor and then float the wall above that (leaving a gap), while attaching the top plate directly to the joists? but not sure of the best approach to make sure everything lines up correctly and is plumb. Also, some of the walls will run parallel to the ceiling joists which presents another problem of attachment. I've read about using L-shaped framing clips and nails, but is that the best approach, and what do you do exactly to accomplish this.

Thanks!
 
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Old 12-21-08, 09:06 PM
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There will be a few different opinions on this I'm sure. Here in Colorado, we also have expansive soil and have to float walls that are framed over concrete in basements most of the time. We usually do what you already described, snap out your wall layout on your floor, plumb up to the bottom of you joists and snap another line. If running parallel, add ladder blocks between the joists at 16" intervals. Then glue and ramset the sill plate, treated wood, to the floor. Measure the distance between you sill plate and floor joists, subtract 3" for the top and bottom plate of your wall and the distance you want for "float" and cut your studs accordingly. We use to only need 2" of float but now it is 3". Once your wall is nailed together, raise it and nail it to the ceiling, then drill a 3/16" or 1/4" hole every 30-36" in you bottom plate of the wall, then use 60d spikes, 6", begin to drive the thru the predrilled hole and before it reaches the sill plate use a speed square to line the plates up then finish driving the nail into the sill plate. Good luck.
 
  #3  
Old 12-23-08, 12:42 PM
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Hi Stickk, thanks for the reply...that sounds easy enough to do and makes perfect sense!!
 
  #4  
Old 01-08-09, 02:49 PM
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Also from Regina

Rudeboy, I've noticed that most of the information on floating walls suggest a 1" to 1 1/2" gap. Most of them state top but some say at the bottom is fine. I've done a number of basements and I find that the real issue with preventing your walls from cracking upon shifting isn't only how you float the walls but how you finish the walls and ceilings.

It seems to me that gyproc secured to the walls will move up and down with movement in your basement floor regardless if your wall is floated or not. If your basement ceiling is gyproc also (done often to get the most clearance in a basement) then there is pressure against the ceiling gyproc and your walls will crack.

I think that if you start your gyproc an inch or so up from the bottom and keep it an inch or so below the roof and then finish with a suspended ceiling... this is the safest way from preventing framed basement wall cracks to appear over time.

In Regina I always "hilti" the first bottom place onto the concrete floor then float the walls an inch at the bottom by nailing the single top plate tight to the floor joists. Drill a hole basically the same size as your nail then nail from the wall bottom plate into the bottom plate on the concrete. Gyproc down to the bottom of the wall bottom plate only. Use 3 1/2" or 4" baseboards in order to hide the float.

Not sure if this helps
 
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Old 01-13-09, 07:19 AM
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SlimSk, thanks for the advice...you know EXACTLY what I'm talking about with the gumbo around here!! Have you done any ICF basements, because that's what I'm dealing with here, and have some questions regarding how to frame up against the insulated forms??
 
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Old 01-25-09, 11:20 AM
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ICF Forms

Rudeboy, sorry for the delay in response. I haven't done any basement framing with ICF formed basements. I really don't see the need to do much different but I've got no expertise in this area
 
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Old 01-26-09, 09:05 PM
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10-4...thought I'd better ask just in case. Thanks again.
 
  #8  
Old 08-30-09, 04:36 PM
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Floating Walls

I have done a number of basements here in Colorado. STICKK provided an excellent description of the framing.

With regard to the gap you need to check with your local building code since it changes.

When you attach the wallboard to the framing you are not allowed to cover the gap - this is why the wallboard will not buckle if the floor moves. The gap will need to be covered by base board if the gap is at the bottom and crown moulding if the gap is at the ceiling. Attach the base board to the sill plate only for gaps at the floor. Attach the crown moulding to the joists only in the case of the gap being at the top of the wall.
 
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Old 08-30-09, 05:13 PM
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Ethandan, welcome to the forums! My daughter's unfinished basement in Denver has the floating wall system. Goofiest thing I ever saw. Help this poor country boy understand things, as no one on the forum thusfar has been able to do.
If the outer walls are poured monolith, the floor is poured slab, how do the interior walls raise and lower with "heave" without breaking the flooring all to pieces? If the entire building picks up with heave, so be it, there would be no need for the interior walls to raise independently.
Just curious.

Larry
 
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